1. FIELD OF THE INVENTION
The present invention relates to the field of games and amusement devices, and more particularly to the field of accessories for table games such as billiards, pool or snooker.
2. DESCRIPTION OF RELATED ART
The table games of pool, billiards and similar games are played by shooting the cue ball with the cue stick and causing it to collide with another ball so as to drive the target ball to a certain location, such as the pocket at the edge of the table. Players often accomplish this objective by causing either the cue ball or the target ball to rebound from a rail cushion in a certain direction. Such shots are known as bank shots. In these shots the player attempts to adjust the angle of incidence of the ball on the cushion so that the angle of rebound will be in the desired direction. If the ball collides elastically with the rail cushion, these angles will be equal. The player will therefore select the location on the rail such that the angle of rebound will be in the direction of the desired target, such as the table pocket. In order to achieve skill at the game, a player must develop the ability to accurately judge these angles. Various learning aids for developing this skill are currently known. These learning aids suffer from two serious drawbacks which cause the aids to be only marginally useful in training a player to judge the impact point viewed from the shooting position.
The first drawback is that the devices are complex and time consuming. For example, use of some shooting aids requires the shooter to walk around the table, position the device, walk back to the shooting position to line up the bank shot, again walk around the table to remove the shooting aid, again return to the shooting position, and finally make the bank shot by estimating the location on the rail of the unmarked impact point, as previously indicated by the device. One such device is disclosed in U.S. Pat. No. 3,463,593 issued to Horan (Cue Ball Angle Computer Including a Curved Mirror for Indicating an Impact Point). A second device is disclosed in U.S. Pat. No. 4,082,270 issued to Josenhans (Billiard Banking Aid).
The second common drawback is that many learning aids must be positioned or adjusted prior to each bank shot. This breaks the shooter's concentration. The previously mentioned Horan and Josenhans devices suffer this drawback. Other devices which require repositioning prior to use include the invention disclosed in German Pat. No. 138,249 issued to Faller (Vorrichtung Zum Erlernen Billiardspiels) and U.S. Pat. No. 4,027,883 issued to Batori (Method for Aiming a Billiards Bank Shot).
To overcome some of these drawbacks, two devices were developed which allow the player to see the shot directly at the time he prepares to shoot and to continue to see it during the entire shooting process. This improvement allows the player to view the entire geometry of the shot from the shooting position both before and after the collisions.
The first such device is disclosed in U.S. Pat. No. 1,297,815 issued to Englehart, which teaches a pool table with mirrors or reflectors located under the rail cushion between the pockets to aid in making bank shots. This device utilizes the optimal principal of equality of the angles of incidence and reflection of rays of light. In making a bank shot, the player can view the target through the mirror, and judge the angle of the bank shot by aiming the ball at the target's reflection. The ball and the target can be kept in view throughout the execution of the shot, so that the player does not have to remember the location of the impact point on the rail cushion. The Englehart device thereby provides advantages over the invention of Horan in assisting a player to develop skill in judging these shots. However, the Englehart patent fails to disclose the use of rail-mirrors which are angled relative to the vertical plane. Thus, the Englehart device suffers from the disadvantage that a player standing at the shooting position would have to bend over the table and assume an unnatural sighting position in order to use the mirror to line up his bank shot. Shooting the cue from this unnatural sighting position is uncomfortable, makes proper execution of the shot more difficult, and, over a period of time, could cause the player to develop a bad shooting posture which would overshadow the benefits of using a rail-mirror learning aid.
The second rail-mirror device is disclosed in U.S. Pat. No. 4,531,732 issued to Harris. To overcome the shortcomings of the Englehart device, the Harris invention incorporated an adjustable rail-mirror. The adjustable rail-mirror disclosed therein is connected to a back plate by a hinge. The rail-mirror can be rotated through a range of angles relative to the vertical plane by adjustment of a small machine screw. The patent further discloses a "cue stick wrench" which is specially designed to fit on a cue stick and is used to engage the machine screw for angular adjustments of the rail-mirror. The mirror is adjustable so that the player can re-adjust the vertical angle of the mirror every time he attempts a bank shot. The patent fails to envision--and does not disclose--that a rail-mirror can be set to one single optimum angle such that once positioned thereto, a shooter standing in a natural sighting position will be able to use the rail-mirror to line up virtually any bank shot on the pool table. This optimum angle is not dependant on a shooter's height because, when shooters lean over to assume a natural shooting position, all shooters' vertical viewing angle of the table is roughly equal. The optimum angle is only dependant on the shooter's distance from the opposing rail. This distance is determined by the width or length of the pool table. Therefore, rail-mirrors can be permanently fixed at predetermined angles. Side-rail-mirrors are fixed to an optimum side-rail-angle, and end-rail-mirrors are fixed to an optimum end-rail-angle. Additionally, angled rail-mirrors with slightly convex surfaces can be used to provide the shooter with an even wider, enhanced viewing range.
The Harris device is overly complex and suffers from various drawbacks. Because the device has movable parts, the mirror is prone to drift and will likely need to be adjusted every time the device is moved from table to table. It also requires periodic adjustments even if moved infrequently. More problems are associated with the cue stick wrench. To use the cue stick wrench, the player must place the wrench on a cue stick tip. Thus, a player would have to re-chalk the cue stick after every use of the wrench. Additionally, cue stick tips vary in diameter, so a player would either have to find a cue stick to match his wrench, or purchase and carry an array of cue stick wrenches. Finally, adjustment of the rail-mirror would be difficult or impossible if the player loses or simply forgets to bring the cue stick wrench. These characteristics of the Harris rail-mirror result in extra effort, increased expense, and decreased portability.
Use of conventional rail-mirror learning aids poses one additional problem. It is beneficial to manufacture the rail-mirror's base from a lightweight material in order to increase the portability of the device. However, lightweight rail-mirrors are more prone to movement. Rail-mirror movement can result from varying causes including vibrations produced by pool balls striking the rail, and by players and passersby inadvertently bumping into the pool table. This creates an additional problem because it is imperative that the rail-mirrors remain under the rail, secure and stationary. If a rail-mirror moves, it can drift out of horizontal alignment with the rail, and the mirror's reflection will indicate an inaccurate banking point on the rail. Even worse, if the rail-mirror moves too far from under the rail, a pool ball can collide into and break the rail-mirror.
None of the existing devices disclose any features to prevent rail-mirror movement. Therefore, a need exists for such improvements. None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.